Method and system for implementing transmitting diversity and receiving diversity

ABSTRACT

The method for implementing transmitting diversity includes receiving a symbol from a destination mobile terminal, by a mobile terminal which is in the same mobile terminal group with the destination mobile terminal, wherein the symbol is also sent from the destination mobile terminal to a base station; and processing, by the mobile terminal, the symbol and transmitting the symbol processed to the base station. The method for implementing receiving diversity includes receiving, by a mobile terminal, a symbol from a base station; finding a destination mobile terminal which is in the same mobile terminal group with the mobile terminal if the mobile terminal is not the destination of the symbol; and forwarding the symbol to the destination mobile terminal. Embodiments of the present invention solve the problem of excessive size of a mobile terminal used for implementing transmitting diversity and receiving diversity, and also reduces bit error rate (BER).

FIELD OF THE TECHNOLOGY

The present invention relates to radio transmission technologies, andparticularly, to methods and systems for implementing transmittingdiversity and receiving diversity.

BACKGROUND OF THE INVENTION

The demand for a better communication quality and a higher transmissionrate is brought forward by a future radio communication system, and aMulti-Input Multi-Output (MIMO) system with multiple antennas isextensively expected for its better channel capacity. A diversitytechnique is of a special importance among massive techniques which areresearched and applied to the MIMO system. According to the diversitytechnique, a signal in a wireless network is transmitted or received viamultiple antennas so as to prevent a system loss; here the system lossis caused by a deep channel fading from which the signal suffers. Theapplication of the diversity technique is based on communicationchannels independent of each other. Generally speaking, two spatialchannels provided by two antennas are considered to be independent ofeach other when the distance between the two antennas is greater thanhalf of a wavelength adopted. For example, in wireless LAN seriesstandards which are compatible with the Bluetooth technology, somestandards may require that two antennas are more than 7 cm away fromeach other to ensure that the spatial channels provided by the antennasare independent of each other, while other standards may require thatthe two antennas are more than 2.8 m away from each other. It can beconcluded that, since multiple antennas cannot be installed intosufficient space in a mobile terminal to ensure the independence ofmultiple communication channels due to the volume limitation of themobile terminal, a receive diversity technique on the downlink and atransmitting diversity technique in uplink cannot be implemented.

In a conventional method, a virtual multiple antenna system consistingof a plurality of mobile terminals is capable of improving spectrumefficiency in the radio communication system. In the virtual multipleantenna system, a plurality of mobile terminals are regarded as onetransmission device. In uplink, signals are transmitted to a basestation which may isolate the signals from each mobile terminal by usingdecoding principles in a spatial multiplex technique.

For example, in uplink of the radio communication system, there are twomobile terminals and a base station, the two mobile terminals can beregarded as a transmission devices capable of transmitting signals tothe base station with the antennas of the mobile terminals. The basestation receives a data stream which is combined by two independent datastreams. It can be seen that the virtual multiple antenna transmissiondevice adopts a spatial multiplexing technique.

FIG. 1 is a schematic diagram illustrating a virtual multiple antennasystem, in which Mobile Terminal 1 transmits signals to a base stationvia an antenna while Mobile Terminal 2 also transmits signals to thebase station via its antenna. In such case, the whole uplink can beregarded as a virtual multiple antenna transmission system which equalsa transmitter with two antennas capable of transmitting signals to thebase station, and the base station receives two independent datastreams.

However, the above scheme is just applicable to the transmission ofuplink and unable to be used in the transmission of downlink, that is tosay, the virtual multiple antenna system is just able to implementtransmitting diversity but unable to implement receiving diversity.

In addition, the spatial multiplexing technique used in the scheme isunable to get a low system Bit Error Rate (BER) while improving spectrumefficiency. Since the signals received in the scheme are the combinationof signals transmitted by a plurality of mobile terminals, theinterference among the signals transmitted by a plurality of mobileterminals imposes on the virtual multiple antenna system a BER higherthan the BER in a single antenna system. Even though the maximumlikelihood (ML) criteria detection which is the most effective errordetection method is adopted in the receiver, the BER of the virtualmultiple antenna system is still relatively high.

SUMMARY OF THE INVENTION

Embodiments of the present invention provide methods and systems forimplementing transmitting diversity and receive diversity so as toreduce BER in wireless transmission.

A system for implementing transmitting diversity includes a destinationmobile terminal in communication with a base station and at least oneother mobile terminal, wherein

-   -   the destination mobile terminal is capable of:    -   transmitting a symbol to the base station; and    -   forwarding the symbol to at least one other mobile terminal        which is in the same mobile terminal group with the destination        mobile terminal.

A system for implementing transmitting diversity includes a mobileterminal in communication with a destination mobile terminal which is inthe same mobile terminal group with the mobile terminal and a basestation, wherein

-   -   the mobile terminal is capable of:    -   receiving a symbol from the destination mobile terminal;    -   processing the symbol received from the destination mobile        terminal; and    -   transmitting the symbol processed to the base station.

A system for implementing receiving diversity includes a mobile terminalin communication with a destination mobile which is in the same mobileterminal group with the mobile terminal and a base station, wherein

-   -   the mobile terminal is capable of:    -   receiving a symbol from the base station;    -   finding the destination mobile terminal if the mobile terminal        is not the destination of the symbol; and    -   forwarding the symbol to the destination mobile terminal.

A system for implementing receiving diversity, includes a destinationmobile terminal in communication with a mobile terminal which is in thesame mobile terminal group with the destination mobile terminal and abase station

-   -   the destination mobile terminal is capable of:    -   receiving a symbol from the base station;    -   receiving a forwarded symbol from the mobile terminal, wherein        the forwarded symbol is originally from the base station;    -   combining the forwarded symbol from the mobile terminal and the        symbol from the base station, and obtaining an estimate value of        an original transmitted symbol.

A system for implementing symbol transmission, includes a base stationin communication with a destination mobile terminal and a mobileterminal which is in the same mobile terminal group with the destinationmobile terminal, wherein

-   -   the base station is capable of:    -   receiving an uplink symbol transmitted directly from the        destination mobile terminal;    -   receiving an forwarded uplink symbol from the mobile terminal,        wherein the forwarded uplink symbol is originally from the        destination mobile terminal;    -   combining the uplink symbol received from the destination mobile        terminal and the uplink symbol forwarded by the at least one        other mobile terminal; and    -   obtaining an estimate value of an original transmitted uplink        symbol.

A method for implementing transmitting diversity includes:

-   -   receiving a symbol from a destination mobile terminal, by a        mobile terminal which is in the same mobile terminal group with        the destination mobile terminal, wherein the symbol is also sent        from the destination mobile terminal to a base station; and    -   processing, by the mobile terminal, the symbol and transmitting        the symbol processed to the base station.

A method for implementing receiving diversity includes:

-   -   receiving, by a mobile terminal, a symbol from a base station;    -   finding a destination mobile terminal which is in the same        mobile terminal group with the mobile terminal if the mobile        terminal is not the destination of the symbol; and    -   forwarding the symbol to the destination mobile terminal.

According to embodiments of the present invention, a mobile terminalfirst transmits a symbol to be transmitted to a base station, to atlease one other mobile terminal in the same mobile terminal group withthe mobile terminal; therefore, transmitting diversity and receivediversity can be implemented with the mobile terminals without increaseof the size of the mobile terminal. Given the same Signal to Noise Ratio(SNR) and system structure, the virtual multiple antenna system inembodiments of the present invention provides a much lower system BERthan the conventional virtual multiple antenna system does.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram illustrating a principle of implementingan uplink spatial multiplex in a conventional method;

FIG. 2 a is a structure diagram illustrating a mobile terminal forimplementing transmitting diversity according to an embodiment of thepresent invention;

FIG. 2 b is a structure diagram illustrating a mobile terminal forimplementing receiving diversity according to an embodiment of thepresent invention;

FIG. 2 c is a structure diagram illustrating a base station according toan embodiment of the present invention;

FIG. 3 is a simplified flow chart of a method for implementingtransmitting diversity on mobile terminals according to the firstembodiment of the present invention;

FIG. 4 is a simplified flow chart of a method for implementing receivingdiversity on mobile terminals according to the second embodiment of thepresent invention;

FIG. 5 is a schematic diagram illustrating a system for implementingtransmitting diversity on mobile terminals according to the fourthembodiment of the present invention;

FIG. 6 is a simplified flow chart of a method for implementingtransmitting diversity on mobile terminals according to the fifthembodiment of the present invention;

FIG. 7 is a schematic diagram illustrating a system for implementingreceiving diversity on mobile terminals according to the sixthembodiment of the present invention;

FIG. 8 is a simplified flow chart of a method for implementing receivingdiversity on mobile terminals according to the seventh embodiment of thepresent invention;

FIG. 9 is a diagram illustrating the result of the emulation of BERperformance in two systems with different SNRs.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is further described as follows in detailaccording to the accompanying drawings and embodiments.

Short range wireless transmission technologies, e.g. the infraredtechnology, Bluetooth technology or Zigbee technology, are effectivelyutilized in embodiments of the present invention to group multiplemobile terminals in the coverage of short range wireless transmission. Amobile terminal is equipped with a single antenna in preferredembodiments of the present invention, while a mobile terminal withmultiple antennas can also be applied in embodiments of the presentinvention. A mobile terminal group can be regarded as a virtual multipleantenna system. Multiple mobile terminals in the virtual multipleantenna system for implementing transmitting or receiving diversitywhich was the privilege of a antenna transmitter or receiver. Theproblem that the mobile terminal has two or more antennas forimplementing a diversity technique and obtaining a diversity gain, whichmakes the size of the mobile terminal excessively large, is avoided.

The short range wireless transmission technology, e.g. the infraredtechnology, Bluetooth technology or Zigbee technology, is applied toembodiments of the present invention. The infrared technology issuitable to low-cost, cross-platform and point-to-point high speed datatransmission applications and is able to provide a transmission rate at16 Mbps at the maximum. It is very convenient to use the infraredtechnology which requires minimum configuration for mobile phone tomobile phone data transmission in general. The infrared technology issupported and employed by a number of software and hardwaremanufacturers around the globe, the infrared technology support is addedinto all mainstream software and hardware platforms at present and usedwidely by mobile computing and communication devices. An infraredinterface is a configuration standard in mobile phones of the newgeneration, which supports data communication between the mobile phonesand computers or other digital devices.

The Bluetooth technology is designed to replace cables and is orientatedin low-cost, short-range and low transmission rate wirelesstransmission. Today the Bluetooth technology has evolved into a personalinformation network technology, which connects devices with embeddedBluetooth chips to provide voice and data access services to achieveautomatic exchange and processing of information. The Bluetoothtechnology can transmit data without aiming precisely at a device with atransmission rate at 1 Mbps.

FIG. 2 a is a structure diagram illustrating a mobile terminal forimplementing transmitting diversity according to an embodiment of thepresent invention. As shown in FIG. 2 a, the mobile terminal includes:

-   -   a first base station communicating unit, capable of transmitting        a symbol to a base station;    -   a first short range wireless unit, capable of transmitting the        symbol to other mobile terminals which are in the same mobile        terminal group with the mobile terminal, and receiving a symbol        from other mobile terminals which are in the same mobile        terminal group with the mobile terminal by using the short range        wireless transmission technology; and    -   an intermediate processing unit, capable of processing the        symbol received by the first short range wireless unit and        transmitting the symbol processed to the first base station        communicating unit which further transmits the symbol processed        to the base station.

The intermediate processing unit may be a space-time coding intermediateprocessing unit which may process the symbol received by the first shortrange wireless unit according to space-time coding rules and transmitsthe symbol processed to the first base station communicating unit. Thefirst base station communicating unit may be a base station timedivision communicating unit which transmits the symbol processed fromthe space-time coding intermediate processing unit to the base stationvia time division.

The first short range unit is further capable of searching for othermobile terminals in the coverage of short range wireless transmissionand transmitting information of the found mobile terminals to the firstbase station communicating unit. The first base station communicatingunit is further capable of transmitting the information to the basestation.

The mobile terminals in embodiments of the present invention may besingle-antenna mobile terminals which are preferred, or multi-antennamobile terminals. The short rang wireless transmission technologyadopted may be the infrared technology, Bluetooth technology or Zigbeetechnology.

The description of the mobile terminal used for implementingtransmitting diversity, as shown in FIG. 2 a, is ended here.

FIG. 2 b is a structure diagram illustrating a mobile terminal forimplementing receiving diversity according to an embodiment of thepresent invention. As shown in FIG. 2 b, the mobile terminal includes: asecond base station communicating unit, a judging unit, a terminalcombining unit, a second short range wireless unit and a terminalexamining and judging unit.

The second base station communicating unit is capable of receiving asymbol from a base station and transmitting the symbol to the judgingunit.

The judging unit is capable of finding a destination mobile terminal ifthe destination of the symbol is not the mobile terminal, and forwardingthe symbol to the second short range wireless unit.

The second short range wireless unit is capable of forwarding the symbolto a destination mobile terminal which is in the same mobile terminalgroup with the mobile terminal by using the short range wirelesstransmission technology. The second short range wireless unit is furthercapable of receiving a symbol from another mobile terminal that is inthe same mobile terminal group with the mobile terminal, andtransmitting the received symbol to the terminal combining unit.

The terminal combining unit is capable of combining the symbol fromanother mobile terminal that is in the same mobile terminal group withthe mobile terminal and the symbol from the base station. The symbolfrom another mobile terminal and the symbol from the base station aresymbols which are sent to another mobile terminal and the base stationby the same mobile station.

The terminal examining and judging unit is capable of examining andjudging the symbol processed by the terminal combining unit to obtain anestimate value of an original transmitted symbol.

In the embodiment, the short rang wireless transmission technologyadopted may be the infrared technology, Bluetooth technology, or Zigbeetechnology. The mobile terminals in embodiments of the present inventionmay be single-antenna mobile terminals or multi-antenna mobile terminalswhile the single-antenna mobile terminals provide better technicaleffect and are preferred in the embodiment of the present invention.

The description of the mobile terminal used for implementing receivingdiversity, as shown in FIG. 2 b, is ended here.

The mobile terminals used for implementing transmitting diversity andreceiving diversity in embodiments shown in FIGS. 2 a and 2 b mayinclude a destination mobile terminal and non-destination mobileterminals, both the destination mobile terminal and non-destinationmobile terminals belong to the same mobile terminal group.

The destination mobile terminal is capable of transmitting a symbol tothe base station, transmitting the symbol to other mobile terminals inthe same mobile terminal group with the mobile terminal by using theshort range wireless transmission technology, receiving symbols from thebase station and other mobile terminals in the same mobile terminalgroup with the mobile terminal, combining and examining the symbolsreceived to obtain the original transmitted symbols. The symbolsreceived from the base station and at least one other mobile terminalare symbols which are sent to the base station and the at least oneother mobile terminal by the same mobile terminal. In addition, thedestination mobile terminal is further capable of searching for othermobile terminals in the coverage of short range wireless transmissionand transmitting the information of the found mobile terminals andmobile terminal group configuration information to the base station.

A non-destination mobile terminal is capable of receiving the symbolfrom the base station, judging the symbol, and, if the destination ofthe symbol is not the current mobile terminal which has received thesymbol, finding and forwarding the symbol to the destination mobileterminal by using the short range wireless transmission technology. Thenon-destination mobile terminal is further capable of receiving a symbolby using the short range wireless transmission technology from anothermobile terminal in the same mobile terminal group with thenon-destination mobile terminal, processing the symbol by usingspace-time coding rules and transmitting the symbol processed to thebase station via time division.

FIG. 2 c is a structure diagram illustrating a base station according toan embodiment of the present invention. As shown in FIG. 2 c, the basestation includes a base station receiving unit, a base stationtransmitting unit, a base station combining unit, a base stationexamining and judging unit, a group setting unit, a group synchronizingunit and a group transmitting unit.

The base station receiving unit is capable of receiving an uplink symboltransmitted directly from a destination mobile terminal and the uplinksymbol from at least one mobile terminal which is in the same mobileterminal group with the destination mobile terminal.

The base station combining unit is capable of combining the receiveduplink symbols to acquire a combined uplink symbol, and transmitting thecombined uplink symbol to the base station examining and judging unit.

The base station examining and judging unit is capable of examining andjudging the combined uplink symbol to obtain an estimate value of anoriginal transmitted uplink symbol.

The base station transmitting unit is capable of transmitting a downlinksymbol to the destination mobile terminal and at least one mobileterminal in the same mobile terminal group with the destination mobileterminal.

The group setting unit is capable of grouping at most N-1 mobileterminals in the coverage of short range wireless transmission from themobile terminal into a mobile terminal group and obtaining mobileterminal group configuration information. Here, N equals the diversityorder supported by the base station.

The group synchronizing unit is capable of synchronizing the mobileterminals in the mobile terminal group.

The base station transmitting unit is further capable of transmittingthe mobile terminal group configuration information received from thegroup setting unit to the mobile terminals in the mobile terminal group.

The description of the base station shown in FIG. 2 c is ended here.

FIG. 3 is a simplified flow chart of a method for implementingtransmitting diversity on mobile terminals according to the firstembodiment of the present invention. The method includes the followingprocesses.

In block 301, a mobile terminal in the service area of a base stationtransmits a request to the base station, requesting to transmit a symbolto the base station.

In block 302, the base station locates the mobile terminal with theGlobal Positioning System (GPS) or via other methods, and estimates thedistance from the base station to the mobile terminal.

In block 303, at most N mobile terminals in the coverage of short rangewireless transmission are grouped into a mobile terminal group, mobileterminals in the mobile terminal group are synchronized and mobileterminal group configuration information is transmitted to the mobileterminals in the mobile terminal group.

In this block, methods for setting the mobile terminal group in thecoverage of short range wireless transmission and transmitting themobile terminal group configuration information to the mobile terminalsin the mobile terminal group are described as follows.

According to the first method, the base station receives the request fortransmitting the symbol from the mobile terminal, groups at most N-1mobile terminals in the coverage of short range wireless transmissionfrom the mobile terminal, and obtains the mobile terminal groupconfiguration information. N equals a diversity order supported by thebase station. The base station synchronizes the mobile terminals in themobile terminal group and transmits the mobile terminal groupconfiguration information to the mobile terminals in the mobile terminalgroup.

According to the second method, a mobile terminal in a self-organizednetwork searches for other mobile terminals in the coverage of shortrange wireless transmission from the mobile terminal and sendsinformation of the found mobiles terminals to the base station. The basestation groups at most N mobile terminals including the mobile terminalinto a mobile terminal group, and obtains the mobile terminalconfiguration information, here N equals the diversity order supportedby the base station. The base station synchronizes the mobile terminalsin the mobile terminal group, and transmits the mobile terminal groupconfiguration information to the mobile terminals in the mobile terminalgroup.

According to the third method, a mobile terminal in a self-organizednetwork searches for N-1 other mobile terminals in the coverage of shortrange wireless transmission from the mobile terminal, forms a mobileterminal group with the found mobile terminals, obtains the mobileterminal group configuration information, and transmits the mobileterminal group configuration information to the base station as well asto the N-1 mobile terminals in the mobile terminal group.

In block 304, being synchronized, the mobile terminals in the mobileterminal group transmit symbols to the base station, and transmit thesymbols which are transmitted to the base station to each other in themobile terminal group by using the infrared technology, Bluetoothtechnology or Zigbee technology.

In block 305, at the following N-1 or 2N-1 symbol periods, N mobileterminals in the group or a part of the N mobile terminals cooperate toform the symbols into an orthogonal matrix or quasi-orthogonal matrix.The space-time coding of the mobile terminal group in uplink isachieved. When the symbols are real number signals, the wholetransmission process requires another N-1 symbol period; and when thesymbols are complex number signals, the whole transmission processrequires another 2N-1 symbol period.

In block 306, the base station combines the received symbols, examinesand judges the symbol combined according to the ML criteria.

The mobile terminals in the embodiment of the present invention may besingle-antenna mobile terminals which attain better technical effect, ormulti-antenna mobile terminals.

FIG. 4 is a simplified flow chart of a method for implementing receivingdiversity on mobile terminals according to the second embodiment of thepresent invention. The method includes the following processes.

In block 401, if a base station transmits a symbol to Mobile Terminal 1,the base station makes sure via the GPS or other locating methods thatMobile Terminal 1 is in the service area of the base station, andsearches for other mobile terminals in the coverage of short rangewireless transmission from Mobile Terminal 1.

In block 402, N-1 mobile terminals which are closest to Mobile Terminal1 form a mobile terminal group with Mobile Terminal 1, the N-1 mobileterminals in the mobile terminal group assist Mobile Terminal 1 inreceiving the symbol.

In this block, methods for grouping Mobile terminal 1 and the N-1 mobileterminals which are closest to Mobile Terminal 1 are described asfollows.

According to the first method, the base station receives a request fortransmitting a symbol from Mobile Terminal 1, and groups Mobile terminal1 and at most N-1 mobile terminals in the coverage of short rangewireless transmission from Mobile Terminal 1 into a mobile terminalgroup.

According to the second method, being a mobile terminal of aself-organized network, Mobile Terminal 1 searches for other mobileterminals in the coverage of short range wireless transmission fromMobile Terminal 1 and sends information of the found mobiles terminalsto the base station. The base station groups N mobile terminalsincluding Mobile Terminal 1 into a mobile terminal group.

According to the third method, Mobile Terminal 1 searches for othermobile terminals in the coverage of short range wireless transmissionfrom Mobile Terminal 1, forms a mobile terminal group with the foundmobile terminals, obtains mobile terminal group configurationinformation, and transmits the mobile terminal group configurationinformation to the base station as well as to other mobile terminals inthe mobile terminal group.

In block 403, having synchronized the mobile terminals in the group, thebase station transmits the mobile terminal group configurationinformation to the mobile terminals in the mobile terminal group, andtransmits the symbol, which is sent to Mobile Terminal 1, to MobileTerminal 1 and at least one mobile terminal in the mobile terminalgroup.

In block 404, upon the receipt of the symbol, at least one mobileterminal in the group except Mobile Terminal 1, forwards the receivedsymbol to Mobile Terminal 1 via the infrared technology, Bluetoothtechnology or Zigbee technology.

Preferably, all other mobile terminals in the group, except MobileTerminal 1, forward the received symbols to Mobile Terminal 1 via theinfrared technology, Bluetooth technology or Zigbee technology

In block 405, Mobile Terminal 1 combines the received symbols, examinesand judges the combined symbol according to the ML criteria to obtain anestimate value of an original transmitted symbol.

According to the third embodiment of the present invention, a multipleantenna system includes two mobile terminals. Provided the base stationhas a single antenna, fading channels between Mobile Terminal 1 andMobile Terminal 2 to the base station are respectively marked as h₁ andh₂. The distance between the two mobile terminals are long enough tokeep the two fading channels independent of each other. In theembodiment of the present invention, the operations of transmitting andreceiving are described from the angle of the mobile terminals.

The following embodiment includes two mobile terminals, e.g. MobileTerminal 1 and Mobile Terminal 2.

FIG. 5 is a schematic diagram illustrating a system for implementingtransmitting diversity on mobile terminals according to the fourthembodiment of the present invention. Solid lines with arrows in thefigure indicate the transmission path of symbols in the wireless LAN anddotted lines with arrows indicate transmission path of symbols via atleast one of the infrared device, Bluetooth device and Zigbee device.

FIG. 6 is a simplified flow chart of a method for implementingtransmitting diversity on mobile terminals according to the fifthembodiment of the present invention. The method includes the followingprocesses.

In block 601, Mobile Terminal 1, which is in the service area of a basestation, transmits a request to the base station for transmitting asymbol, the base station responds to the request. At the same time,Mobile Terminal 2, which is in the coverage of short range wirelesstransmission from Mobile Terminal 1, also transmits a request to thebase station for transmitting a symbol.

In block 602, Mobile Terminal 1 and Mobile Terminal 2 are grouped into agroup, mobile terminal group configuration information is obtained andtransmitted to Mobile Terminal 1 and Mobile Terminal 2. Mobile Terminal1 and Mobile Terminal 2 process symbols according to space-time codingrules here the space-time coding process includes coding, according tothe principle that a diversity gain may be obtained after processing thesymbols at a receiver, the symbols to be transmitted by the mobileterminals in the mobile terminal group at a receiver, and obtaining thesymbols to be transmitted by the mobile terminals at different symbolperiods.

In the block, several methods can be employed to group Mobile Terminals1 and 2, which are hereinafter described as follows.

According to the first method, the base station receives a request fortransmitting a symbol from Mobile Terminal 1 or 2, and groups the twomobile terminals into a group.

According to the second method, provided Mobile Terminals 1 and 2 are ina self-organized network, Mobile Terminal 1 searches for Mobile Terminal2 in the coverage of short range wireless transmission from MobileTerminal 1 and sends the information of Mobile Terminal 2 to the basestation, or Mobile Terminal 2 searches for Mobile Terminal 1 in thecoverage of short range wireless transmission from Mobile Terminal 2 andsends the information of Mobile Terminal 1 to the base station. The basestation groups the two mobile terminals into a group.

According to the third method, Mobile Terminal 1 searches for MobileTerminal 2 in the coverage of short range wireless transmission fromMobile Terminal 1, forms a mobile terminal group with Mobile Terminal 2,obtains mobile terminal group configuration information, and transmitsthe mobile terminal group configuration information to the base stationas well as to Mobile Terminal 2.

In block 603, after being synchronized, Mobile Terminal 1 transmitsto-be-transmitted symbol s₁ to the base station and transmits symbol s₁via the infrared technology, Bluetooth technology, or Zigbee technologyto Mobile Terminal 2 at symbol period 1. At the same time, MobileTerminal 2 transmits to-be-transmitted symbol s₂ to the base station andtransmits symbol s₂ via the infrared technology, Bluetooth technology,or Zigbee technology to Mobile Terminal 1.

In block 604, Mobile Terminal 1 and Mobile Terminal 2 transmit symbols−s₂* and s₁* to the base station respectively at symbol period 2, hereis the conjugation of s. The symbols transmitted at symbol period 1 andsymbol period 2 from the two mobile terminals form a 2*2 orthogonalmatrix, so that the base station may filter out the signals from eachmobile terminal by using a weighted combination algorithm whencalculating an estimate value of an original transmitted signal.

The signal received by the base station at symbol period 1 is expressedas:

r ₁ =h ₁ s ₁ +h ₂ s ₂ +n _(1,)

and the signal received by the base station at symbol period 2 isexpressed as:

r ₂ =−h ₁ s ₂ *+h ₂ s ₁ *+n _(2.)

Here n₁ and n₂ indicate an additive Gaussian white noise received by thebase station at symbol period 1 and symbol period 2 respectively.

The calculation performed by the base station on the signals to beexamined includes:

ŝ ₁ =h ₁ *r ₁ +h ₂ r ₂*

ŝ ₂ =h ₂ *r ₁ −h ₁ r ₂*.

Here the ŝ is the estimate value of the s. The symbols from MobileTerminal 1 and Mobile Terminal 2 are respectively filtered via theprocession of weighted combination.

In block 605, the base station examines and judges, according to the MLcriteria, the original transmitted symbols s₁ and s₂, and obtains anestimate value.

In the embodiment, it should be noted that each mobile terminal justassistants other mobile terminals which are in the same mobile terminalgroup with the mobile terminal in transmitting a symbol. Function ofinterpreting contents of the signals from other mobile terminals isdisabled in the mobile terminals.

FIG. 7 is a schematic diagram illustrating a system for implementingreceiving diversity on mobile terminals according to the sixthembodiment of the present invention. Solid lines with arrows in thefigure indicate the transmission path of symbols in a wireless LAN anddotted lines with arrows indicate transmission of symbols via theinfrared technology, the Bluetooth technology or the Zigbee technology.

FIG. 8 is a simplified flow chart of a method for implementing receivingdiversity on mobile terminals according to the seventh embodiment of thepresent invention, in which the base station is supposed to transmitsymbol s to Mobile Terminal 1. The embodiment includes the followingprocesses.

In block 801, a base station determines, via a positioning method suchas the GPS, that Mobile Terminal 1 is in the service area of itself, andsearches for other mobile terminals in the coverage of short rangewireless transmission from Mobile Terminal 1.

In block 802, Mobile Terminal 2, which is closest to Mobile Terminal 1,forms a mobile terminal group with Mobile Terminal 1. Mobile terminalgroup configuration information is obtained and transmitted to MobileTerminals 1 and Mobile Terminal 2 which will assist Mobile Terminal 1 inreceiving information. The mobile terminals in the group aresynchronized as well.

In the block, the method used for grouping Mobile Terminal 2, which isclosest to Mobile Terminal 1, and Mobile Terminal 1 is similar to themethod adopted in block 602, and thus will not be described repeatedlyherein.

In block 803, at the next symbol period after synchronizing MobileTerminal 1 and Mobile Terminal 2 in the mobile terminal group, the basestation transmits a symbol s to Mobile Terminal 1 and Mobile Terminal 2via channels h₁ and h₂ respectively, here h₁ and h₂ are the channelsfrom the base station to Mobile Terminal 1 and Mobile Terminal 2.

Signal received by Mobile Terminal 1 is expressed as:

r ₁ =h ₁ s+n _(1;)

and signal received by Mobile Terminal 2 is expressed as:

r ₂ =h ₂ s+n _(2,)

here n₁ and n₂ indicate the additive Gaussian white noise received byMobile Terminal 1 and Mobile Terminal 2 respectively.

In block 804, Mobile Terminal 2 transmits the received symbol r₂ toMobile Terminal 1, and Mobile Terminal 1 combines symbols received fromthe base station directly and from Mobile Terminal 2. If signal s issupposed to be transmitted from the base station to Mobile Terminal 2,Mobile Terminal 1 shall transmit signal r₁ to Mobile Terminal 2, andMobile Terminal 2 combines symbols received from the base stationdirectly and from Mobile Terminal 1. The structure of a systemcontaining Mobile Terminal 1 and Mobile Terminal is similar to thesystem shown in FIG. 7, but the arrows on the dotted lines points toopposite directions. In this block, the infrared technology, theBluetooth technology or the Zigbee technology may be adopted for thetransmission.

The processing of combining the symbols received by Mobile Terminal 1 isexpressed as:

ŝ=h ₁ *r ₁ +h ₂ *r _(2.)

In block 805, Mobile Terminal 1 examines and judges signal s from thebase station by using the ML criteria.

According to the eighth embodiment of the present invention, the virtualmultiple antenna system in the following embodiment includes four mobileterminals. A base station in the embodiment has a single antenna. Fadingchannels from Mobile Terminals 1, 2, 3 and 4 to the base station aremarked as h₁, h₂, h₃ and h₄ respectively. The four mobile terminals arefar enough from each other to keep the four fading channels independentof each other.

When the mobile terminals transmits signals to the base station and whentransmitted symbols s₁, s₂, s₃ and s₄ are real number signals, atransmit matrix comprised of the symbols transmitted by the four mobileterminals at four consecutive symbol periods is expressed as:

$\begin{bmatrix}s_{1} & s_{2} & s_{3} & s_{4} \\{- s_{2}} & s_{1} & {- s_{4}} & s_{3} \\{- s_{3}} & s_{4} & s_{1} & {- s_{2}} \\{- s_{4}} & {- s_{3}} & s_{2} & s_{1}\end{bmatrix}.$

If the transmitted signals are complex number signals, a transmit matrixcomprised of the symbols transmitted at eight consecutive symbol periodsis expressed as:

$\begin{bmatrix}s_{1} & s_{2} & s_{3} & s_{4} \\{- s_{2}} & s_{1} & {- s_{4}} & s_{3} \\{- s_{3}} & s_{4} & s_{1} & {- s_{2}} \\{- s_{4}} & {- s_{3}} & s_{2} & s_{1} \\s_{1}^{*} & s_{2}^{*} & s_{3}^{*} & s_{4}^{*} \\{- s_{2}^{*}} & s_{1}^{*} & {- s_{4}^{*}} & s_{3}^{*} \\{- s_{3}^{*}} & s_{4}^{*} & s_{1}^{*} & {- s_{2}^{*}} \\{- s_{4}^{*}} & {- s_{3}^{*}} & s_{2}^{*} & s_{1}^{*}\end{bmatrix}.$

Here the method of transmitting the symbols at the first four symbolperiods is identical with the method of transmitting real numbersignals, and signals transmitted at the last four symbol periods areconjugations of the signals transmitted at the first four symbolperiods.

Transmit matrixes are not limited to the above matrixes, any orthogonalmatrix or quasi-orthogonal matrix is acceptable as long as a receivermay filter out a signal transmitted from a mobile terminal afterperforming a weighted combination.

Having received the symbols, the base station performs the weightedcombination on the received signals. When the received signals are realnumber signals, the signals received at symbol period 1, symbol period2, symbol period 3 and symbol period 4 are expressed as:

r ₁ =h ₁ s ₁ +h ₂ s ₂ +h ₃ s ₃ h ₄ s ₄ +n _(1;)

r ₂ =−h ₁ s ₂ +h ₂ s ₁ −h ₃ s ₄ +h ₄ s ₃ +n _(2;)

r ₃ =−h ₁ s ₃ +h ₂ s ₄ +h ₃ s ₁ −h ₄ s ₂ +n _(3;)

r ₄ =−h ₁ s ₄ −h ₂ s ₃ +h ₃ s ₂ +h ₄ s ₁ +n _(4;)

here n₁ to n₄ indicate the additive Gaussian white noise received by thebase station at symbol period 1, symbol period 2, symbol period 3 andsymbol period 4 respectively.

When the transmitted signals are complex number signals, the signalsreceived at symbol period 1 to symbol period 8 are expressed as:

r ₁ =h ₁ s ₁ +h ₂ s ₂ +h ₃ s ₃ h ₄ s ₄ +n _(1;)

r ₂ =−h ₁ s ₂ +h ₂ s ₁ −h ₃ s ₄ +h ₄ s ₃ +n _(2;)

r ₃ =−h ₁ s ₃ +h ₂ s ₄ +h ₃ s ₁ −h ₄ s ₂ +n _(3;)

r ₄ =−h ₁ s ₄ −h ₂ s ₃ +h ₃ s ₂ +h ₄ s ₁ +n _(4;)

r ₅ =h ₁ s ₁ *+h ₂ s ₂ *+h ₃ s ₃ *+h ₄ s ₄ *+n _(5;)

r ₆ =−h ₁ s ₂ *+h ₂ s ₁ *−h ₃ s ₄ *+h ₄ s ₃ *+n _(6;)

r ₇ =−h ₁ s ₃ *+h ₂ s ₄ *+h ₃ s ₁ *−h ₄ s ₂ *+n _(7;)

r ₈ =−h ₁ s ₄ *−h ₂ s ₃ *+h ₃ s ₂ *+h ₄ s ₁ *+n _(8;)

Here n₁ to n₈ indicate the additive Gaussian white noise received by thebase station at symbol period 1 to symbol period 8 respectively.

The base station calculates the to-be-examined values which will be sentto base station examining and judging units. When the transmittedsignals are real number signals, the signals to be sent to four basestation examining and judging units are:

ŝ ₁ =h ₁ r ₁ +h ₂ r ₂ +h ₃ r ₃ +h ₄ r _(4;)

ŝ ₂ =h ₂ r ₁ −h ₁ r ₂ −h ₄ r ₃ +h ₃ r _(4;)

ŝ ₃ =h ₃ r ₁ +h ₄ r ₂ −h ₁ r ₃ −h ₂ r _(4;) and

ŝ ₄ =−h ₄ r ₁ −h ₃ r ₂ +h ₂ r ₃ −h ₁ r _(4.)

When the transmitted signals are complex number signals, the signals tobe sent to the four base station examining and judging units are:

ŝ ₁ =h ₁ *r ₁ +h ₂ *r ₂ +h ₃ *r ₃ +h ₄ *r ₄ h ₁ r ₅ *+h ₂ r ₆ *+h ₃ r ₇*+h ₄ r _(8;)*

ŝ ₂ =h ₂ *r ₁ −h ₁ *r ₂ −h ₄ *r ₃ +h ₃ *r ₄ +h ₂ r ₅ *−h ₁ r ₆ *−h ₄ r ₇*+h ₃ r _(8;)*

ŝ ₃ =h ₃ *r ₁ +h ₄ *r ₂ −h ₁ *r ₃ −h ₂ *r ₄ +h ₃ r ₅ *+h ₄ r ₆ *−h ₁ r ₇*−h ₂ r _(8;)* and

ŝ ₄ =−h ₄ *r ₁ −h ₃ *r ₂ +h ₂ *r ₃ −h ₁ *r ₄ −h ₄ r ₅ *−h ₃ r ₆ *+h ₂ r₇ *−h ₁ r _(8.)*

Finally, the base station examines and judges the four originaltransmitted signals s₁, s₂, s₃ and s₄ from the four mobile terminalsrespectively by using the ML criteria based on the to-be-examinedvalues.

When the base station transmits the symbol to a destination mobileterminal, at the next symbol period of the synchronization in the mobileterminal group, the base station transmits symbol s, which is supposedto be sent to the destination mobile terminal, to Mobile Terminals 1, 2,3 and 4 via channels h₁, h₂, h₃ and, i.e., the four channels from thebase station to Mobile Terminal 1, Mobile Terminal 2, Mobile Terminal 3and Mobile Terminal 4 respectively. Hence the signals received by MobileTerminals 1 to 4 are:

r ₁ =h ₁ s+n _(1;)

r ₂ =h ₂ s+n _(2;)

r ₃ =h ₃ s+n _(3;) and

r ₄ =h ₄ s+n _(4.)

Here n₁ to n₄ indicate the additive Gaussian white noise received byMobile Terminals 1 to 4 respectively.

When symbol s is supposed to be transmitted by the base station toMobile Terminal 1, that is to say, Mobile Terminal 1 is the destinationmobile terminal. Mobile Terminals 2 to 4 transmit received symbols r₂ tor₄ to Mobile Terminal 1 by using the infrared technology, the Bluetoothtechnology or the Zigbee technology. Mobile Terminal 1 combines thereceived symbols, examines and judges the combined symbol to obtain theoriginal transmitted symbol. If symbol s is supposed to be transmittedby the base station to Mobile Terminal 2, that is to say, MobileTerminal 2 is the destination mobile terminal, Mobile Terminal 1, MobileTerminal 3 and Mobile Terminal 4 transmit received symbols r₁, r₃ and r₄to Mobile Terminal 2 by using the infrared technology, the Bluetoothtechnology or the Zigbee technology, Mobile Terminal 2 combines thereceived symbols, examines and judges the combined symbol to obtain anoriginal transmitted symbol. If Mobile Terminal 3 or 4 is thedestination mobile terminal, the process can be deduced accordingly.

The weighted combination performed by a terminal combining unit in thedestination mobile terminal with the received signals is expressed as:

ŝ=h ₁ *r ₁ +h ₂ *r ₂ +h ₃ *r ₃ +h ₄ *r _(4.)

Finally, the destination mobile terminal examines and judges theoriginal transmitted symbol s from the base station by using the MLcriteria.

It should be noted that, in the embodiment, other mobile terminals inthe same mobile terminal group just assistant the destination terminalin receiving a signal. Function of interpreting contents of signals fromother mobile terminals should be disabled.

In the following description, the performance of the technical schemeprovided by embodiments of the present invention is compared with theperformance of the conventional virtual multiple antenna system in anemulation of a system BER. The two systems have similar structures, thatis to say, each of the systems has two mobile terminals in a wirelessnetwork, and that the fading channels on the downlink from the basestation to the two mobile terminals and the fading channels in uplinkfrom the two mobile terminals to the base station in each of the systemsfollow a complex Gaussian distribution with zero mean and unit variance.The fading channels can be expressed as:

${h_{m} = {{{Normal}\left( {0,\frac{1}{\sqrt{2}}} \right)} + {\sqrt{- 1} \cdot {{Normal}\left( {0,\frac{1}{\sqrt{2}}} \right)}}}},{m = 1},2.$

Here h_(m)(m=1,2) indicates a fading channel on the downlink from MobileTerminal m to the base station, or a fading channel in uplink from thebase station to Mobile Terminal m.

The system processes 2×10⁶ independent Monte Carlo channel samples at atime.

FIG. 9 is a diagram illustrating the result of the BER performanceemulation in the two systems with different SNRs. The line with crossedmarks in the figure indicates the BER in the conventional virtualmultiple antenna system, the line with squares indicates the BER in asingle antenna transmit and single antenna receive system, the line withtriangles indicates the BER of transmit diversity in uplink in anembodiment of the present invention, and the line with circles indicatesthe BER of receive diversity on downlink in an embodiment of the presentinvention.

As shown in the diagram, though the conventional virtual multipleantenna system achieves relatively high frequency efficiency by using aspace multiplexing technique, offers poor BER performance. With the sameSNR, the BER in the conventional virtual multiple antenna system ishigher than the BER in the conventional single antenna transmit andsingle antenna receive system. In embodiments of the present invention,the transmit diversity in uplink and the receive diversity on downlinkis achieved with the infrared technology, Bluetooth technology or Zigbeetechnology in the system. The system in embodiments of the presentinvention offers a transmission rate which equals to the transmissionrate in the conventional single antenna transmit and single antennareceive system, but obtains a diversity gain which greatly improves theBER performance of the system. With the same SNR, the BER in the systemof embodiments of the present invention is far lower than the BER in theconventional single antenna transmit and single antenna receive system.

In embodiments of the present invention, the communication between thebase station and the mobile terminals may be performed in bothdirections at the same time by using a frequency division duplex (FDD)technique, that is to say, a frequency is capable of transmittingsignals on the downlink from the base station to the mobile terminalswhile another frequency is capable of transmitting signals in uplinkfrom the mobile terminals to the base station.

In addition, the division of uplink and downlink can also be achievedwith time division duplex (TDD) on the same frequency, that is to say,in one time slot all communication frequencies are used in uplink fromthe base station to the mobile terminals while in another time slot allcommunication frequencies are used in downlink from the mobile terminalsto the base station. Therefore the FDD or the TDD may be used forallocating the uplink and downlink.

It should be noted that in embodiments of the present invention, themobile terminal group may includes a single antenna mobile terminalgroup or a multiple antenna mobile terminal group, and the mobileterminals may be single antenna mobile terminals or multiple antennamobile terminals. Single antenna mobile terminal group and singleantenna mobile terminals provide better technical effect in theembodiments of the present invention.

It should be emphasized that the above-described embodiments,particularly, any embodiments, are merely possible examples ofimplementations, merely set forth for a clear understanding of theprinciples of the invention. Many variations and modifications may bemade according to the above preferred embodiments without departingsubstantially from the spirit and principles of the invention. All suchmodifications and variations are intended to be included herein withinthe scope of this disclosure and the above preferred embodiments andprotected by the following claims.

1. A system for implementing transmitting diversity, comprising adestination mobile terminal in communication with a base station and atleast one other mobile terminal, wherein the destination mobile terminalis capable of: transmitting a symbol to the base station; and forwardingthe symbol to at least one other mobile terminal which is in the samemobile terminal group with the destination mobile terminal.
 2. Thesystem of claim 1, wherein the destination mobile terminal is furthercapable of: searching for other mobile terminals in coverage of shortrange wireless transmission from the destination mobile terminal; andtransmitting information of the found mobile terminals to the basestation.
 3. The system of claim 1, wherein the destination mobileterminal is a single antenna mobile terminal.
 4. A system forimplementing transmitting diversity, comprising a mobile terminal incommunication with a destination mobile terminal which is in the samemobile terminal group with the mobile terminal and a base station,wherein the mobile terminal is capable of: receiving a symbol from thedestination mobile terminal; processing the symbol received from thedestination mobile terminal; and transmitting the symbol processed tothe base station.
 5. The system of claim 4, wherein processing andtransmitting the symbol comprising: processing the symbol received fromthe destination mobile terminal via space-time coding rules; andtransmitting the symbol processed via the space-time coding rules to thebase station via time division.
 6. A system for implementing receivingdiversity, comprising a mobile terminal in communication with adestination mobile which is in the same mobile terminal group with themobile terminal and a base station, wherein the mobile terminal iscapable of: receiving a symbol from the base station; finding thedestination mobile terminal if the mobile terminal is not thedestination of the symbol; and forwarding the symbol to the destinationmobile terminal.
 7. A system for implementing receiving diversity,comprising a destination mobile terminal in communication with a mobileterminal which is in the same mobile terminal group with the destinationmobile terminal and a base station; the destination mobile terminal iscapable of: receiving a symbol from the base station; receiving aforwarded symbol from the mobile terminal, wherein the forwarded symbolis originally from the base station; combining the forwarded symbol fromthe mobile terminal and the symbol from the base station, and obtainingan estimate value of an original transmitted symbol.
 8. The system ofclaim 7, wherein combining and obtaining the estimate value of theoriginal transmitted symbol comprising: examining and judging the symbolcombined, and obtaining the estimate value of an original transmittedsymbol.
 9. A system for implementing symbol transmission, comprising abase station in communication with a destination mobile terminal and amobile terminal which is in the same mobile terminal group with thedestination mobile terminal, wherein the base station is capable of:receiving an uplink symbol transmitted directly from the destinationmobile terminal; receiving an forwarded uplink symbol from the mobileterminal, wherein the forwarded uplink symbol is originally from thedestination mobile terminal; combining the uplink symbol received fromthe destination mobile terminal and the uplink symbol forwarded by theat least one other mobile terminal; and obtaining an estimate value ofan original transmitted uplink symbol.
 10. The system of claim 9,wherein combining and obtaining the estimate value of the originaltransmitted symbol comprising: examining and judging the combined uplinksymbol, and obtaining the estimate value of an original transmitteduplink symbol.
 11. The system of claim 9, wherein the base station isfurther capable of transmitting a downlink symbol to the destinationmobile terminal and the at least one other mobile terminal.
 12. Thesystem of claim 9, wherein the base station is further capable of:grouping at most N-1 mobile terminals in the coverage of short rangewireless transmission from the mobile terminal into a mobile terminalgroup and obtaining mobile terminal group configuration information,wherein N is the diversity order supported by the base station;synchronizing the mobile terminals in the mobile terminal group; andtransmitting the mobile terminal group configuration information to themobile terminals in the mobile terminal group.
 13. A method forimplementing transmitting diversity, comprising: receiving a symbol froma destination mobile terminal, by a mobile terminal which is in the samemobile terminal group with the destination mobile terminal, wherein thesymbol is also sent from the destination mobile terminal to a basestation; and processing, by the mobile terminal, the symbol andtransmitting the symbol processed to the base station.
 14. The method ofclaim 13, wherein processing the symbol and transmitting the symbolprocessed to the base station comprises: processing, by the mobileterminal, the symbol according to space-time coding rules; andtransmitting the symbol processed to the base station via time division.15. The method of claim 13, further comprising: setting up the mobileterminal group in advance in the coverage of short range wirelesstransmission, obtaining mobile terminal group configuration informationand transmitting the mobile terminal group configuration information toat least one other mobile terminal in the mobile terminal group.
 16. Themethod of claim 13, wherein receiving the symbol from the destinationmobile terminal comprises: receiving the symbol from the destinationmobile terminal via a short range wireless transmission technology. 17.The method of claim 16 wherein receiving the symbol via the short rangewireless transmission technology comprises: receiving the symbol by themobile terminal via the infrared technology, Bluetooth technology, orZigbee technology.
 18. The method of claim 14, wherein transmitting thesymbol processed to the base station via time division comprises:transmitting, if the symbol is a real number signal and the number ofmobile terminals in the mobile terminal group is N, the symbol or thereciprocal value of the symbol to the base station at N consecutivesymbol periods by the N mobile terminals.
 19. The method of claim 18,wherein the N*N symbols or the reciprocal values of the N*N symbolstransmitted at the N symbol periods are determined by an N-orderorthogonal matrix, each column of the orthogonal matrix corresponds tothe signals transmitted by a mobile terminal in the mobile terminalgroup at N consecutive symbol periods and each row of the orthogonalmatrix corresponds to the signals transmitted by all mobile terminals inthe mobile terminal group at a symbol period.
 20. The method of claim14, wherein transmitting the symbol processed to the base station viatime division comprises: transmitting, if the symbol is a complex numbersignal and the number of mobile terminals in the mobile terminal groupis N, the symbol, the reciprocal value of the symbol, the conjugation ofthe symbol or the negative conjugation of the symbol to the base stationat 2N consecutive symbol periods by the N mobile terminals.
 21. Themethod of claim 20, wherein the 2N*N transmitted signals are determinedby a 2N*N quasi-orthogonal matrix, N*N elements in the first N rows ofthe 2N*N quasi-orthogonal matrix constitute an N-order orthogonal matrixand N*N elements in the last N rows are the negative conjugation of theN*N elements in the first N rows, wherein the N is not equal to
 2. 22.The method of claim 13, after transmitting the symbol processed to thebase station, further comprising: combining, by the base station, thesymbol processed from the mobile terminal and the symbol from thedestination mobile terminal, examining and judging the symbol combined,and obtaining an estimate value of an original transmitted symbol.
 23. Amethod for implementing receiving diversity, comprising: receiving, by amobile terminal, a symbol from a base station; finding a destinationmobile terminal which is in the same mobile terminal group with themobile terminal if the mobile terminal is not the destination of thesymbol; and forwarding the symbol to the destination mobile terminal.24. The method of claim 23, further comprising: setting up the mobileterminal group in advance in the coverage of short range wirelesstransmission, obtaining mobile terminal group configuration informationand transmitting the mobile terminal group configuration information toa plurality of mobile terminals in the mobile terminal group.
 25. Themethod of claim 23, wherein forwarding the symbol to the destinationmobile terminal comprises: forwarding the symbol to the destinationmobile terminal via the infrared technology, Bluetooth technology, orZigbee technology.
 26. The method of claim 23, after forwarding thesymbol to the destination mobile terminal, further comprising: combiningsymbols received by the destination mobile terminal.
 27. The method ofclaim 26, further comprising: examining and judging symbol combined bythe destination mobile terminal by using the maximum likelihood (ML)criteria, and obtaining an estimate value of an original transmittedsymbol.